The invention relates to a Flash based memory comprising a Flash translation layer and method for storing a file therein.
Flash based memories provide a significant advantage over other storage media like hard disks and optical media like DVD or BD: Flash memories need no moving parts to be accessed and thus cannot become inaccessible due to impacts impairing operation of the moving parts. This makes Flash a well suited storage device for mobile applications where rough conditions may occur.
One of such applications is the capturing of images, either stills or video frames. Flash based memories are used as storage in end consumer devices like digital still cameras and digital video cameras. Flash based memories can be found in MP3-players, also. Further, Flash based memories gain more and more importance as storage devices for professional digital film cameras.
Commonly, Flash memories have an internal storage management taking care of wear-levelling and error correction. Applications interact with the internal storage management via a so-called Flash translation layer (FTL). The FTL emulates a file system, for instance FAT32.
Theoretically, FAT32 file systems may have any size but practically very large FAT32 file systems become slow and inefficient. Therefore, in some operating systems FAT32 file system size is limited to 32 GB. Furthermore, the maximum possible file size on FAT32 is one byte less than 4 GByte and the number of files per directory which can be handled by FAT32 is limited to 1000. And due to the fact that clusters, the smallest logical amounts that can be allocated to hold a file, are large in FAT32, lots of storage capacity is wasted for stuffing bits to clusters to which files significantly smaller than the cluster size are stored.
FAT on removable media may be replaced by Universal Disk Format (UDF), a format specification of a file system for storing files on optical media. An FTL emulating a UDF appears from outside as a sectored storage medium.
Flash based memories have the disadvantage that—at least today—the price per GB is high compared to other storage media like optical disks.
Therefore, there is an ongoing effort in the art to exploit the storage capacity of Flash based memories as efficiently as possible.